Welcome to the world's largest online community of tomato growers! If this is your first visit, please take a few moments and register to become a member of our community and have full access to all of our forums. (some are exclusive to members only) For more details about how to register, please click here.

i started my seeds in baggies, moved them to 2 1/2 x 2 1/2 x 3 1/2 inch pots, i'm using LED lights and a fan, lights on 16 hours, fan on and off different times during the day, leaves strated to turn purple, so turned heat mats under trays on,(basement was in low to mid 60's) also have a heater blowning towards the plants, (about 6 feet away, temperature of soil is around 80 degs, most of purple leaves are gone now, only watered when pots felt light, about a dozen or so plants are starting to have leaves that are drying up and looking terrible, any ideas?--- thanks tom

The damage looks like edema to me. For some reason I had this badly last year when recently potted tomato seedlings were moved under the LED light - that is not a plant light, just an LED shop light. Apparently edema is a common problem under narrow spectrum LED.

If your seedlings were raised under them from day one without a problem, it could be that you triggered the edema water-uptake problem while trying to tweak the temperature with heaters and fans.
If I were you I would try to get them into natural light as soon as possible. I would not worry about temperatures in the 60's for tomato seedlings, and a bit of leaf purpling is not harmful. Exposure to cooler temperatures will activate cold tolerance genes so that the plants are better able to cope with outdoor conditions. The edema OTOH is not good, it can cause damage that can't be repaired and it may take a while for plants to recover. The worst affected of my seedlings were stunted for some time after and although they did eventually return to normal, they flowered much later than their normal time. So you don't want to let this continue or get any worse.

I've been dealing with similar. Look at your stem structure. Not at all a straight cell structure.
Root hairs missing in patches. Those areas have the 'crud'. Simultaneously the leaves fold and
bend. Seemingly overnight.
My issue came with the snow melt. Air quality changes from dry to very humid with all the rain.
A few fungus gnats. Not an infestation. One of the life stages is not interested in the sticky traps.
As if immune.
I lost just a quarter of a tray. Perfectly healthy plants next to some that went down. Some of those
survived. I sprayed with stylet-oil then buried the stems deeper. I still do not have a solution or if
two things are going on simultaneously.
Not convinced it is the lights since I have 600 healthy plants and lost about 30.
Some of those I left on the end of the deck headed for the garbage un-cared-for. Some have
survived even ignored. But clearly stunted in growth.

Oakley, I was just reading that humidity is a factor as well, for 'edema' or 'intumescence'. There are a number of contributing causes, one of them is that UV-B is involved in stomatal function, at least for some cultivars it can cause a failure to open and transpire when needed, resulting in what is basically a water injury to the plant. High humidity evidently causes this as well.

That looks so familiar to me. I have been battling with this years. It seems to affect some varieties more than others. Black Cherry and some potatoe leaf varieties used to be the worst. Surprisingly this year I did not see any of this problem. I moved my seedling shelves to a room, which gets morning sun and used fluorescent lights for tomatoes. Also I skipped my normal bottom watering habit.
Earlier years the ones, which got the problem and did not die usually started to recover when moved to the greenhouse. That is why I try to get the plants to the greenhouse as soon as possible.

Sari

__________________"I only want to live in peace, plant potatoes and dream."
- Moomin-troll by Tove Jansson

ok thanks for the info, seems like that's what it is, keeping the heat mat under them and cold damp air blowing on them, not a good thing, also went from full spectrum flouresant lights to LED, might have been a mistake. or not, ----thanks tom

I had edema on my pepper plants for several years and didn't know what it was. I thought the blisters were egg masses of some kind of miner or invisible pest. The peppers were under fluorescents and iirc mostly 'daylight' bulbs on the blue end, so they were getting some UV/blue but I was setting them up away from the windows to keep them warmer, and I guess it wasn't enough.

I never did see it on tomatoes until last year, and it was not only under 6500 K LED but also away from the window in that case, and they got it bad. And just as you said, Sari, some varieties were worse - one of my crosses out of Black Cherry was the worst affected by far.

Now I'm reading that this is a common problem for winter growers of kales as well, and that is in greenhouses but in winter some of us don't get enough light anyway. It looks different on kale, and now I'm realizing this is a problem I had on my gailan this winter, both under the LED and also in a window with fluorescents. IMO my potting mix is just a bit too soggy, in addition to being a dreary and cloudy late winter. The gailan seems to have outgrown the problem though, as was pretty bad on the earliest leaves. Some other crops don't seem to be affected as readily - Bok Choy and lettuce have both done fine even under LED and away from windows.

Anyway now that I know the causes, I will always have an eye out for this in winter growing. And I think the combo of lights and sunniest window is always going to be my best bet.

here's one of the worst ones, almost like stem is drying up on some, and got some kind of mold on stem in the middle section, all i can think of is the warm humid soil from turning heat mats back on, and the fan blowing cool damp air on them, was going to try repotting them into deeper pots like solo cups, up to where the stems are greener , to see if they start to root above the smooth part of stem, you think i should some how try and remove that mold or whatever that is first?-- thanks---tom

I'm betting they are toast. I have the same issue as you know. My healthy seedlings are
at least six time the size of my suffering varieties. I did mist my affected stems with sty-let.
I have plenty to test...I'll try copper as well. Then pot-up deep.
I just think they are too young to over-come the mold issues. I'll give it a go but I did start
another two trays for those affected.
I have no issues at all on peppers or any other garden seedlings and I have many. I do expect to
see tomato leaf mold outside if the wet weather continues. Pro-active with copper and sty-let.

This pic is 5 minutes ago...sad six pack. Surrounded by KARMApink, a EmmyGWR, and a good
solid batch of Artsy variegated.
Seedlings that far behind are rarely worth it. Coin toss if you want to give it a go...

Oh my, now that I see a moldy stem I remember another time - only four of about a hundred were affected and they went down hard like that. I didn't know what the cause was, so I isolated them and they didn't die but at least 3 of the 4 were too stunted to bother planting out.

I think the mold is a sign of serious vascular damage in the main stem - I wouldn't waste time planting them deeper or trying to save them. And I would keep them away from others, in case it has a chance to spread.

I am remembering that I had signs of vascular trouble on other plants after plant out that year as well - swellings at the leaf nodes for example - but at the end of season when I cut them down there was no sign of a vascular disease having come from the soil - stems were solid and healthy at the base. So it was another tomato mystery unsolved - other than obvious problems with my container mix that year being the wrong stuff entirely for containers.

At the time the seedlings went down, I had also been peeling a bad batch of potatoes around the time I potted up, so I was suspecting some potato disease had gotten to them. I never found any proof of that though, and in the end I could only conclude it was physiological.

Another suspect in these potting incidents, for me, is lumps of peat in the mix that were not at all hydrated. The bulk seems all good but there are these super-dry pellets hidden away... I think it can be bad news when tomato roots get around those, and it sucks moisture out of them. But again I am speculating... When I read about edema/intumescence having multiple causes I understand how difficult it is to pinpoint one thing.

One thing for sure, those four seedlings were potted up at the same time into the same mix, as well as being the same lot of seeds (while three others were fine). So what happened to the tail end of that mix, what was different? Nothing fundamentally. Could it be unsoaked bits of peat?